Ukrainian President Volodymyr Zelenskyy addressed Parliament in London on Wednesday, as the United Kingdom announced plans to increase its deliveries of "lethal aid."
"I have come here to stand before you on behalf of the brave," Zelenskyy said after receiving a standing ovation from members of both Houses of Parliament.
He thanked Britain for training troops "who will be then deployed to the front line -- front line -- skilled, eager and equipped to win."
The visit was Zelenkyy's second known international trip since the Russian invasion began almost a year ago. The trip underscored the United Kingdom's "unbreakable friendship" with Ukraine, Prime Minister Rishi Sunak in a statement.
MORE: Russia-Ukraine live updatesDowning Street announced the surprise visit on Wednesday morning, saying it comes as the United Kingdom expands it training for Ukrainian armed forces. Zelenskyy also met with King Charles at Buckingham Palace on Wednesday, after saying he wanted to thank him for his support.
"The King was an Air Force pilot, and In Ukraine every Air Force pilot is a king," Zelenskyy told Parliament members.
Zelenskyy and Sunak were expected to discuss what the United Kingdom's described as its "two-pronged" approach to aiding Ukraine, which included a "surge" in the supply of military equipment and long-term support with training for troops.
"As part of today's talks, the Prime Minister will offer to bolster the UK's training offer for Ukrainian troops, including expanding it to fighter jet pilots to ensure Ukraine can defend its skies well into the future" U.K. officials said in a statement.
About 10,000 Ukrainian troops have been trained in the United Kingdom in the last six months, officials said. More than 20,000 additional troops are expected to be trained this year.
British officials said they expected the program to continue scaling throughout the year. Zelenskyy on Wednesday planned to meet with U.K. defense officials to discuss the training.
"I am proud that today we will expand that training from soldiers to marines and fighter jet pilots, ensuring Ukraine has a military able to defend its interests well into the future," Sunak said in a statement ahead of the visit.
British officials said they planned on Wednesday to also announce further sanctions in response to Russia's invasion. The sanctions will target people who've helped Russian President Vladimir Putin build personal wealth, along with "companies who are profiting from the Kremlin's war machine," officials said.
Zelesnkyy also laid out a proposal under which any country that acts as an aggressor or terrorist state will eventually be held financially responsible for its crimes.
He called an eventual victory for Ukraine and its allies the "most important victory of our lifetime," which would amount to a warning for Russia and any other countries considering attacking a sovereign neighbor.
"Any aggressor is going to lose," he said.
ABC News' Joe Simonetti, Guy Davies and Zoe Magee contributed to this report.